A battery of tests of perceptual asymmetry is developed for use with actively psychotic patients. Perceptual asymmetry, which is presumed to be due to the specialization of cerebral hemispheres, refers to the fact that healthy subjects with intact brains more readily perceive certain types of stimuli when they are presented to the right sensory field, and others when they are presented to the left sensory field. Normal adults and patients with schizophrenic or schizoaffective illnesses and affective psychoses are tested with versions of the Dichotic Words Test, the Dichotic Loudness Test, the Dichotic Chords Test, the Visual Words Recognition Test, and the Visual Dot Localization Test.